Device for giving warning of fire



Nov. 6, 1928. Y 1,690,486

E. HALF DEVICE FOR GIVING WARNING OF FIRE Filed Sept. 18,' 1924 with thin walls.

PatentedA Nov. 6, 1928.

UNITED- STATES vEDIIiIONI) HALF, OF PARIS, FRANCE.

DEVICE FOB. GIVING WARNING OF FIRE.

Application led September 18, 1924, Serial No. 738,432, and in France Kay 10, 1824.

This invention relates to improvements in devices for giving warning of fire, based upon the known principle of the expansion of air contained in a metallic box having very thin walls, the air in expanding operating a mechanical device adapted to close or break an electric circuit, thus operating any kind of alarm signal, such for instance as an electric bell. The present invention refers more particularly to means for eliminating the mechanical devices generally employed up to the present, replacing them by a simple apparatus which 'functions in a perfect manner.

The characteristic features of the apparatus are the' following z- The air contained in the box with metallic walls, or even in a receptacle of glass, porcelain or the like, is caused when expanding to operate directly, with the intervention of a tube placed in an appropriate position, a small 'piston or other analogous part which when moved closes or opens an electric circuit so as to release or set in motion the alarm signal.

The piston or the like may also operate a needle or some kind of lever mechanism so as to close an electric circuit in. connect-iomwith the alarm signal.

The accompanying drawing shows, by way of example, one method of carrying out the invention.

In the drawings Fig. 'l is an elevation ot the Whole apparatus, with a portion in section.

Fig. 2 is a part section to alargar scale showing the device attached to a metallic box, according to a second method of Vcarrying out the invention. s l

Fig. 3 is also a section of the device illus trating a third method of carrying out the invention.

The device for giving warning of lire comprises in the usual manner a metallic box l This box may be round or of any other appropriate shape. The bottom or any other portion thereof may be strengthcned or reeniorced according to requirement.

Attached to the top plate 2 of the box l is a tube 3 in which is adapted to slide a small piston 4. The lower portion ot this piston is bevelled off and is adapted to rest on the extremity of a contact screw The -tube may be provided below the piston with an annular ledge or disc having a perforation '6. This is intended to regulate the quantity of air operating on the piston 4.

The diameter of the piston is slightly less than the inner diameter of the tube 3 so as to leave between the walls a space enabling air to pass in small quantities and to escape to the outside through a perforation 7 ornied in the cap at 9, or in some other suitable portion of the tube 3, for instance as shown at 9. in Fig. 8.

The tube is provided with a second contact screw 8.

The operation is as follows. When the surrounding temperature rises steadily, the air in they interior of the reservoir expands. if this expansion of air is rapid, the said air rapidly aiiects the piston 4, which slides in. the tube, and leaving the contact 5 causes the breakage of the circuit which isvconnected to an alarm bell adapted to be rung when the circuit is broken or in connection with any other suitable alarm.

On the other hand when the increase oil temperature is gradual, the expansion of the air contained in the box l will also be gradual, and the air will have time to escape between the outside of the piston and the Wall of the tube without the piston being operated.

Fig. 2 shows a second constructional embodiment of the invention in which the tube is bent at right angles. In this case the air expansion box is placed at the side and the tube is fixed to a. plate2 at the side thereof.

The apparatus operates in the same manner as already described with reference to Fig. l.

At Figure 3, the tube in which the piston slides'is inclined. Moreover, the piston after sliding causes the closure of a circuit in connection with the alarm means.

For this purpose the upper extremity of the tube is provided with an insulating cap l() with a central contact screw 1l.

When the piston 4 is pushed upwards owing to the 'sudden expansion of the air contained in the box 2, which expansion is caused by a sudden rise in the surrounding temperature, the piston comes into contact with the contact screw 11 and the electric circuit is closed to the alarm device which immediately cornes into operation.

It is evident that the piston described can be replaced by any part of any shape which Will fulfil the same object, such for instance as a ball or the like, and that Without depart# ing from the principle of the' invention.

Moreover, the expansion box can be of any shape', round, hexagonal, oval, truncated or otherwise, permitting expansion and certain operation of the device. I

What I claim and desire to secure by Letters Patent of the United States of America 1s f l 1. ln a switch adapted to be operated by a sudden rise of temperature, the. combination of a reservoir for air having walls with a high coecient of thermal conductivity, a

tube forming "a cylinder lin connection with the' said reservoir, aslidable plug loosely mounted in the saidcylinder, and having its lower end bevelled, means for retaining the plug in. the said cylinder, means above the said plug for allowing air to escape to the outside, and contacts adapted to be operated when `the plug is moved, substantially as described.

' 2. ln a switch adapted to loe-operated hy a sudden rise of temperature, the combination of a reservoir for air having walls with a mounted in the said cylinder, and having its lower end bevelled, an insulated contact screw passing through the walls of the Saul cylinder, 'che inner end of the screw supporting the bevelled end ot the plug, another Contact screw mounted on the cylinder, means for admitting an' to Ithe lower end of the cylinder and means for allowing air to escape from the upper end of the cylinder, substantially as set forth.

ln witness whereof l aiiixrny signature. EDMOND HALF. 

